Picea is a genus of evergreen coniferous trees in the family Pinaceae, comprising 35 species. It is commonly known as Spruce and is native to northern temperate and boreal (taiga) regions.
Picea species are large trees, 20 - 60 m tall when mature, and can be distinguished by their whorled branches and conical form. The leaves (needles) are attached singly to the branches in a spiral fashion. Each needle is on a small peg-like structure called a pulvinus and shed when it is 4 - 10 years old, leaving the branches rough with the retained pulvinus.
Spruce is one of the most important woods for paper making industry, as it has long wood fibres which bind together to make strong paper. It was cultivated in vast area for this purpose.
Picea is a popular ornamental tree, admired for its evergreen, symmetrical narrow-conic growth habit. It can also be grown as hedges, and in rock gardens. P. abies and P. omorika are extensively used as Christmas trees. Some dwarf cultivars such as Alberta White Spruce, Picea glauca var. albertiana 'Conica', is a popular garden plant.
Picea orientalis (Caucasian Spruce, Oriental Spruce) is a large, evergreen tree native to the Caucasus and adjacent northeast Turkey. It can grow to 30 - 45 m tall and with a trunk diameter of up to 1.5 m. Picea orientalis is a popular ornamental tree in large gardens, highly valued in northern Europe and the USA for its attractive foliage and the ability to grow in wide range of soil. It is also grown for Christmas tree, timber and paper production.
Picea glauca (White Spruce) is a medium-sized evergreen tree growing to 15 - 30 m tall, with a trunk diameter of up to 1 meter. It is native to north of North America, from central Alaska east to Newfoundland, and south to northern Montana, Michigan, Maine and Wisconsin. The bark of the tree is thin and scaly, flaking off in small circular plates 5 - 10 cm across. The crown is a narrow conic in young trees, becoming cylindric in older trees. The leaves are needle-like, 10-20 mm long, glaucous blue-green above and blue-white below. The cones are pendulous, slender cylindrical, 3 - 7 cm long and 1.5 cm broad, with thin, flexible scales 15 mm long, with a smooth rounded margin. The cones are green or reddish, maturing to a pale brown color 4 - 6 months after pollination. The seeds are black, 2 - 3 mm long, with a slender , 5 -8 mm long pale brown wing. Picea glauca is a major economic importance in Canada for its wood, harvested for paper-making. It is also used as Christmas tree.
Picea grows well in full sun, in moisture-retentive but well-drained, neutral to acid soil. Propagation is by seed in spring; ripewood cuttings in summer. Pests and diseases are Adelgids and honey fungus.